1. Field of the Invention
The present invention relates to an attachment such as a high temperature attachment arranged around a specimen in an X-ray apparatus and an X-ray apparatus having the attachment.
2. Description of the Related Art
There have been known an X-ray apparatus, which measures X-rays from a specimen when the specimen is irradiated with X-rays from an X-ray source, such as X-rays diffracted by the specimen, by using X-ray detection means such as an X-ray counter. There have been also known An X-ray apparatus, which performs such X-ray measurement by using a specimen housed in an attachment such as a high temperature attachment.
In an X-ray apparatus of such kind, a main role of X-ray detection means is to detect X-rays from a specimen. However, if there are no measures for excluding undesired X-ray from an attachment housing the specimen, the X-ray detection means may also detect the undesired X-rays, causing a result of X-ray detection to be incorrect.
In order to solve such a problem, an X-ray apparatus having a structure such as shown in FIG. 4 has been proposed in which a slit 52 is provided between a specimen S and an X-ray detector 51. In FIG. 4, the specimen S is housed in a temperature regulator 53, which is one of attachments for changing temperature of the specimen S. The slit 52 is constructed with a plurality of walls 54 arranged in parallel along a line shown by an arrow A.
The X-ray detector 51 may comprise a PSPC (Position Sensitive Proportional Counter), which is a one-dimensional X-ray detector. As well known, the PSPC 51 has a lateral slot 56 for receiving X-rays and, when X-rays are incident on any position of the slot 56, outputs a signal corresponding to the position, that is, the diffraction angle of X-ray, and having a level corresponding to an intensity of the X-ray.
In the X-ray apparatus shown in FIG. 4, X-rays radiated from an X-ray source F is collimated by a divergence-limiting slit 57 and directed to the specimen S. When the X-rays incident on the specimen S satisfies the Bragg""s diffraction condition with respect to crystal lattice plane of the specimen S, the X-rays are diffracted by the specimen S. The diffracted X-rays pass through the spaces defined by the walls 54 constituting the slit 52 and are incident on the slot 56 of the PSPC 51.
In the above-described conventional X-ray apparatus, when X-rays pass through an X-ray window 59 of the temperature regulator 53, the X-rays are scattered, resulting in scattered X-rays as undesired X-rays. Although the slit 52 is provided for preventing the undesired X-rays from being incident on the X-ray detector 51, the degree of prevention of undesired X-rays is not enough to exclude the effect of undesired X-rays.
An object of the present invention is to prevent undesired X-rays generated from other locations than a specimen from entering into an X-ray detector.
The inventors of the present invention had conducted various experiments on prevention of undesired X-rays incident on the X-ray detector and have found that it is effective to block undesired X-rays in the vicinity of location at which the undesired X-rays are generated.
(1) In order to achieve the above object, an attachment mounted on a specimen support portion of an X-ray apparatus, according to the present invention, is featured by comprising a cover member covering a specimen and a scattered ray excluding member provided between the cover member and the specimen. The scattered ray excluding member defines a through-hole having an inlet opening having a large area on the side of the cover member and an outlet opening having a small area on the side of the specimen.
According to this attachment, the scattered ray excluding member prevents undesired X-rays from being mixed in travelling paths of X-rays incident on the specimen and diffracted X-rays from the specimen, so that it is possible to perform a highly precise X-ray measurement.
(2) In the above-mentioned attachment, it is preferable that width and height of the inlet opening on the cover member side are larger than those of the outlet opening on the specimen side. Thus, incident angles of the X-rays incident on the specimen in width and height directions can be made large.
(3) In this attachment, the scattered X-ray excluding member may be arranged on the X-ray incident side of the specimen. Thus, it is possible, by the scattered X-ray excluding member, to shield undesired X-rays resulting from scattering of X-rays when the X-rays from an X-ray source pass through the cover member covering the specimen.
(4) In this attachment, the scattered X-ray excluding member can be formed by vertical wail members and lateral wall members. That is, the scattered X-ray excluding member can take in the form of an enclosure having a pair of vertical walls and a pair of lateral walls. With such an enclosure covering a space having square cross section, excludability of scattered X-rays becomes high compared with a scattered X-ray excluding member takes in a dome or semi-cylindrical form.
(5) In this attachment, the cover member may be formed of a visually transparent and X-ray transmitting material and have a semi-spherical form. By forming the cover member of the visually transparent material, it is possible to perform a measurement while watching the specimen. By the employment of the semi-spherical configuration of the cover member, it is easy for a user to handle the cover member.
X-rays diffracted by the specimen impinge to different positions of the inner surface of the cover member according to diffraction angles of X-rays. If the cover member is not in the semi-spherical form, the length of the traveling paths of X-rays within the wall of the cover member are changed according to the impinging positions, resulting in change of absorption of X-rays. This may require taking some steps for compensating the change of absorption of X-rays.
In contrast, since the semi-spherical form is employed in the present invention for the cover member, the length of the traveling paths of X-rays within the wall of the cover member becomes uniform regardless of the impinging positions of X-rays on the inner surface of the cover member. Thus, there is no need to make any compensation.
(6) Further, the attachment mentioned above may have a main body portion to be mounted on the sample support portion of the X-ray apparatus and the cover member can be detachably fixed to the main body portion.
(7) In the attachment having the cover member detachably fixed to the main body portion, the cover member may be mounted on the main body portion by forming a female thread on an inner peripheral surface of the cover member, forming a male thread on an outer peripheral surface of the main body portion and screwing the cover member onto the main body portion. With such construction employed, the cover member can be firmly fixed to the main body portion with a very simple work.
(8) The attachment may further comprise at least one of heater means for heating the specimen, cooling means for cooling the specimen, moisture regulator means for changing moisture condition around the specimen and environment regulation means for setting a gas environment of the specimen different from the atmosphere environment.
The attachment having the heating means constitutes a so-called high temperature attachment and that having the cooling means constitutes a so-called low temperature attachment.
(9) A high temperature attachment to be mounted on a specimen support portion of an X-ray apparatus, according to the present invention, is featured by comprising a specimen table for mounting a specimen thereon, heater means for heating the specimen table, a cover member covering the specimen and a scattered X-ray excluding member provided between the cover member and the specimen. The scattered ray excluding member defines a through-hole having an inlet opening having a large area on the side of the cover member and an outlet opening having a small area on the side of the specimen.
With this high temperature attachment, the scattered ray excluding member prevents undesired X-rays from being mixed in travelling paths of X-rays incident on the specimen and X-rays diffracted by the specimen, so that it is possible to perform highly precise X-ray measurement.
(10) An X-ray apparatus according to the present invention is featured by comprising specimen support means for supporting a specimen, an X-ray source for generating X-rays irradiating the specimen, X-ray detection means for detecting X-rays diffracted by the specimen and an attachment mounted on the specimen support means. The attachment has any one of the constructions mentioned above.
With this X-ray apparatus, the scattered ray excluding member prevents undesired X-rays from being mixed in travelling paths of X-rays incident on the specimen and diffracted X-rays from the specimen, so that it is possible to perform a highly precise X-ray measurement.
(11) In the above-mentioned X-ray apparatus, the X-ray detection means may comprise a two-dimensional X-ray detector. The two-dimensional X-ray detector can detect distribution of X-rays in a plane. That is, it can detect X-rays two-dimensionally. The X-ray detector may be a dry X-ray plate, an X-ray film or a plane storage phosphor. Alternatively, the X-ray detector may comprise a CCD (Charge Coupled Device) sensor including two-dimensionally arranged CCDs.
The dry X-ray plate is a flat X-ray detection element composed of a base substrate formed of a relatively hard material and having a suitable area and an emulsion film containing silver halide as a main constituent and painted on one of or both surfaces of the base substrate. By developing an exposed dry X-ray plate, a two-dimensional distribution of X-ray can be obtained on the surface of the dry X-ray plate.
The X-ray film is a flat X-ray detection element composed of a thin, flexible plastic film and an emulsion film containing silver halide as a main constituent and painted on one of or both surfaces of the base plate. By developing an exposed X-ray film, a two-dimensional distribution of X-ray can be obtained on the surface of the X-ray film.
The X-ray detector comprising the plane storage phosphor is an energy storage type radiation-detecting element. The storage phosphor is formed by painting a surface of a flexible film or a flat plate type film, etc., with storage fluorescent material such as, for example, BaFBr:Er2+ fine crystals. The storage phosphor can store X-ray, etc., in the form of energy and can discharge the energy externally as light by irradiating it with stimulation pumping light such as laser light.
That is, when the storage phosphor is irradiated with X-rays, an image of X-ray is stored in the storage phosphor as a latent image of energy and, when the storage type fluorescent material is irradiated with stimulation pumping light such as laser light, the energy is discharged externally as light. By detecting the light by photoelectric tube, etc., diffraction angle and intensity of the X-ray contributed to the formation of the latent image can be measured. Sensitivity of the storage phosphor is about 10 to 60 times that of the conventional X-ray film and has a wide dynamic range from 106 to 108.
The plane type CCD sensor includes a plurality of CCDs arranged two-dimensionally on an X-ray receiving surface. The CCD sensor includes an electrode array formed by linearly or two-dimensionally arranging a plurality of electrodes on an insulating film formed on, for example, a silicon substrate, the electrode array being arranged correspondingly to a X-ray receiving slot of the X-ray detector.
When portions of the CCD sensor corresponding to the respective electrodes of the electrode array thereof are irradiated with X-ray, electric charges are stored below the electrodes and the electric charges are transferred externally by sequentially applying a voltage between the electrodes and the substrate.
In the X-ray apparatus using the two-dimensional X-ray detector, two-dimensionally dispersed X-rays are detected simultaneously and, therefore, possibility of detecting undesired X-rays becomes high. However, when the scattered ray excluding member of the present invention is used, it is possible to reliably prevent an exposure of the two-dimensional X-ray detector with undesired X-rays.